The findings, based on interviews with 8- to 12-year-olds, show how resilient youngsters can be even when facing something as frightening as cancer.
The results also indicate that children's perceptions often differ from those of their parents, whose own negative feelings about the experience may shade how they think their children are coping, the researchers said.
"What we are finding is very reassuring," said Dr. Smita Bhatia, lead author and a pediatric cancer specialist at City of Hope National Medical Center in Duarte, Calif.
Parents should be encouraged to know that young survivors "can indeed put their cancer behind them," she said.
The study appears in February's edition of the journal Pediatrics, published Monday.
Sebastian Sanchez-Luege, a 9-year-old patient of Bhatia's who was diagnosed with an aggressive lymphoma at age 6 but was not involved in the study, said he feels normal and happy.
"I kind of feel more guarded by God now," said the Orange County, Calif., boy, "and maybe a little bit happier." That's partly because friends who were distant during his disease "now are like flocking over me," he said.
Now cancer-free, Sebastian underwent grueling treatment, including massive doses of radiation and chemotherapy and a stem-cell transplant in 2002, said his mother, Carmen Luege. She remembers him vomiting 10 times a day, suffering mouth sores so severe he couldn't eat and taking morphine intravenously to dull the pain.
"Through all of that, to me what is amazing is, he remembers good things," Luege said. "He doesn't have nightmares, he's adjusted back into his life, he's full of life."
Cancer strikes an estimated one in 300 to 350 U.S. youngsters before age 20. With improved treatments, survival rates for many childhood cancers have risen sharply in recent decades. More than 75 percent of American children with cancer survive at least five years, compared with around 60 percent in the mid-1970s, according to the National Cancer Institute.
"Survival will always remain the ultimate goal," but as treatments and outcomes improve, long-term well-being should also be a target, the researchers wrote.
They questioned 90 children who had been successfully treated for cancer at least a year earlier, 72 youngsters undergoing treatment, and a control group of 481 children who had never had cancer.
The questions focused on physical issues, including pain and activity restrictions; psychological functioning, including fear of death, worrying and feeling inferior; and outlook on life, including happiness and optimism. Scores ranged from 1 to 5, with 5 being most positive.
As expected, children undergoing treatment had lower overall scores than both other groups. But the survivors' overall scores were high, averaging 4.15, slightly above the 4.05 average for the control group. Brain cancer survivors had lower overall scores than the control group.
She noted that only three survivors in the study had had brain cancer, which makes up about 20 percent of childhood cancers and can be particularly debilitating. A more representative sample might have produced less favorable results, said Schmidt, who was not involved in the research.
The study was funded in part by the National Cancer Institute.
By Lindsey Tanner